/*
 * @(#)ValueTaglet.java 1.12 03/12/19
 * 
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. SUN
 * PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.tools.doclets.internal.toolkit.taglets;

import com.sun.javadoc.*;
import com.sun.tools.doclets.internal.toolkit.Configuration;
import com.sun.tools.doclets.internal.toolkit.util.*;
import java.util.*;

/**
 * An inline Taglet representing the value tag. This tag should only be used
 * with constant fields that have a value. It is used to access the value of
 * constant fields. This inline tag has an optional field name parameter. If the
 * name is specified, the constant value is retrieved from the specified field.
 * A link is also created to the specified field. If a name is not specified,
 * the value is retrieved for the field that the inline tag appears on. The name
 * is specifed in the following format: [fully qualified class name]#[constant
 * field name].
 * 
 * This code is not part of an API. It is implementation that is subject to
 * change. Do not use it as an API
 * 
 * @author Jamie Ho
 * @since 1.4
 */

public class ValueTaglet extends BaseInlineTaglet {
	
	/**
	 * Construct a new ValueTaglet.
	 */
	public ValueTaglet() {
		name = "value";
	}
	
	/**
	 * Will return false because this inline tag may only appear in Fields.
	 * 
	 * @return false since this is not a method.
	 */
	public boolean inMethod() {
		return true;
	}
	
	/**
	 * Will return false because this inline tag may only appear in Fields.
	 * 
	 * @return false since this is not a method.
	 */
	public boolean inConstructor() {
		return true;
	}
	
	/**
	 * Will return false because this inline tag may only appear in Fields.
	 * 
	 * @return false since this is not a method.
	 */
	public boolean inOverview() {
		return true;
	}
	
	/**
	 * Will return false because this inline tag may only appear in Fields.
	 * 
	 * @return false since this is not a method.
	 */
	public boolean inPackage() {
		return true;
	}
	
	/**
	 * Will return false because this inline tag may only appear in Fields.
	 * 
	 * @return false since this is not a method.
	 */
	public boolean inType() {
		return true;
	}
	
	/**
	 * Given the name of the field, return the corresponding FieldDoc.
	 * 
	 * @param config the current configuration of the doclet.
	 * @param tag the value tag.
	 * @param name the name of the field to search for. The name should be in
	 *        <qualified class name>#<field name> format. If the class name is
	 *        omitted, it is assumed that the field is in the current class.
	 * 
	 * @return the corresponding FieldDoc. If the name is null or empty string,
	 *         return field that the value tag was used in.
	 * 
	 * @throws DocletAbortException if the value tag does not specify a name to
	 *         a value field and it is not used within the comments of a valid
	 *         field.
	 */
	private FieldDoc getFieldDoc(Configuration config, Tag tag, String name) {
		if (name == null || name.length() == 0) {
			// Base case: no label.
			if (tag.holder() instanceof FieldDoc) {
				return (FieldDoc) tag.holder();
			} else {
				// This should never ever happen.
				throw new DocletAbortException();
			}
		}
		StringTokenizer st = new StringTokenizer(name, "#");
		String memberName = null;
		ClassDoc cd = null;
		if (st.countTokens() == 1) {
			// Case 2: @value in same class.
			Doc holder = tag.holder();
			if (holder instanceof MemberDoc) {
				cd = ((MemberDoc) holder).containingClass();
			} else if (holder instanceof ClassDoc) {
				cd = (ClassDoc) holder;
			}
			memberName = st.nextToken();
		} else {
			// Case 3: @value in different class.
			cd = config.root.classNamed(st.nextToken());
			memberName = st.nextToken();
		}
		if (cd == null) {
			return null;
		}
		FieldDoc[] fields = cd.fields();
		for (int i = 0; i < fields.length; i++) {
			if (fields[i].name().equals(memberName)) {
				return fields[i];
			}
		}
		return null;
	}
	
	/**
	 * {@inheritDoc}
	 */
	public TagletOutput getTagletOutput(Tag tag, TagletWriter writer) {
		FieldDoc field = getFieldDoc(writer.configuration(), tag, tag.text());
		if (field == null) {
			// Reference is unknown.
			writer.getMsgRetriever().warning(tag.holder().position(),
					"doclet.value_tag_invalid_reference", tag.text());
		} else if (field.constantValue() != null) {
			return writer.valueTagOutput(field,
					Util.escapeHtmlChars(field.constantValueExpression()),
					!field.equals(tag.holder()));
		} else {
			// Referenced field is not a constant.
			writer.getMsgRetriever().warning(tag.holder().position(),
					"doclet.value_tag_invalid_constant", field.name());
		}
		return writer.getOutputInstance();
	}
}
